Hard gelatin capsules are used in great numbers for the packaging of pulverized, granulated or pelletized medicines. Such capsules are typically made in two halves which can be joined together, that is, a lower capsule portion and an upper capsule portion. The benefits provided by this form of packaging medicines are two fold, first, the production of the hard gelatin capsules can be done in an economical manner and, second, very precise dosing of the medicine to be packaged is possible. Other advantages provided are the possibility of filling a hard gelatin capsule with substances of various types; and that the production of the hard gelatin capsules, and the filling and sealing of the same, can be performed in different manufacturing locations. The medicine packager orders the two-piece hard gelatin capsules from specialized production firms, and the capsules are then processed by the packager on machines designed for filling and sealing hard gelatin capsules. In contrast, a completely different methodology has been previously used in the packaging of liquid medicines. In order to capsulate liquid medicines, soft gelatin capsules were preferably used, so that the fluid was filled in the capsule in the same single processing operation as that in which the capsules were produced (as described, for instance, in the British Pat. No. 564,538). Thus, to package liquid medicines, the medicine producer had only two alternatives, either procurement of expensive machines of this kind for production of soft gelatin capsules himself at his manufacturing plant--with all of the attendant problems involved in the manufacture of gelatin capsules--or contracting out the packaging of liquid medicines to places of business specially set up for filling gelatin capsules.
A challenge was thus created within the pharmiceutical industry to develope new technology which would improve upon the method then available for filling liquid medicines in hard gelatin capsules. Besides the elimination of the difficulties described above, such a novel method would provide the further advantage that the machinery previously used for filling these capsules with powders, or other solids, could also be put to use for filling liquid medicines into hard gelatin capsules. A method and an apparatus for filling liquid medicines into hollow containers, which were either prefabricated or created by the joining together of two halves of hard gelatin capsules, has been disclosed in the German Offenlegunschrift No. 26 50 649. In this known method, the filling of a two-piece hard gelatin capsule, which is sealed at the juncture between the two capsule halves is accomplished according to the injection principle. It has been demonstrated that this mode of operation enables the attainment of very good results in the filling of liquid medicines into hard gelatin capsules. Inspite of this advance, the sealing of the two-piece hard gelatin capsule remains a problem. In order to alleviate this seal problem and attain optimal results in the filling of liquid medicines into hard gelatin capsules, it is extremely desirable to develop a one-piece capsule which could be produced by simple means.